1. Field of the Invention
This invention relates to extruding machines, and more particularly to machines having roller dies between which extruded plastic material is formed into sheets.
2. Prior Art
An extruder-roller die may comprise an extruding device in which a plastic or rubber material is mixed and propelled along the length of a cylinder or barrel, through a discharge orifice, and introduced between cooperating die rolls which form the material to the finished dimensions. The material is discharged into the area between the rolls under heavy pressure.
It has been found in practice that as the material is introduced into the opening between the die rolls, excessively high pressures may be exerted on the rolls themselves, which may occur at a time when the extruder is delivering to the rolls a volume of material in excess of what the calender rolls can deliver as output. This same excessive pressure can also occur due to an unusually high viscosity of the material being formed. This could build up an accumulation of material which the rolls could not immediately handle, and which would require the shutting down of the entire apparatus. The shutdown would include the attendant removal of the excess material and cleaning of the equipment after moving portions of the equipment away from the extruder, on rails or wheels, before it can be reassembled and put back into productive use. This machine downtime reduces efficiency and increases maintenance costs. The need for portions of the machine to be mounted on rails or wheels also adds to the cost thereof. An attempt at improving the roller die machines is shown in U.S. Pat. No. 3,115,672 where the roller dies move orthogonally apart to permit cleaning and inspection thereof, which orthogonal movement, however, inherently puts a higher strain on the machinery.
Accordingly, the present invention provides a new and improved arrangement for supporting, adjusting, and releasing or backing-off a pair of rolls in a roll support frame, attached to an extruder machine.
It is an object of the present invention to provide an improved roll support and release mechanism.
It is a further object of the present invention to provide an improved retraction mechanism for die rolls in an extruding machine.